Pneumatic jar ramming molding machines



Oct., l, 1929. w. LEWIS PNEUMATIC JAR RAMMING MOLDING MACHINES Filed OCL. l2, 1926 5 Sheets-Sheet @iS/wrom i 47m/MEX.

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PNEUMATICI JAR RAMMING MOLDING MACHINES Filed 0ct. 12, 1926 3 Sheets-Sheet 2 FIG. 2;

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ATTORNEY Patented @et l, i929 ica WILFRED LEWIS, 0F HAVERFORD, PENNSYLVANIA, ASSIGNOR TO THE TABOR -bil-MTU'- FACI'URING COMPANY, OF PHILADELPHIA, PENNSYLVANTA, A. CORPORATON OF PENNSYLVANIA PNEUMATIC JAR BAMMING MOLDING MACHINES Application filed October 12, 1936. Serial No. 141,090.

Objects of the present invention are to prevent an excessive overrun of the table; to avoid material variations in the length of the stroke of the table; to provide for shifting the jarring valve at very slow speeds so that the exhaust will always be wide open when it opens at all; to avoid destructive eifects in the nature of hammer blows and to cushion the valve stem; to give the exhaust valve a lead in closing so as to retard the table andinsure proper Contact of the mold with it; to ada-pt the operation of the machine to and make it equally effective under different loads imposed by different flasks; and, in the case of shockless machines, to keep the anvil and the table in step.

Other objects of the invention will appear from the following description and the invention will be claimed at the end of the description, and the description will be given with reference to the accompanying drawings forming part hereof and illustrating an embodiment of the invention and in which drawinffs tligure 1 is a sectional view of a shockless jarring machine embodying all the features of the invention.

Figure 2 is a view of the operating valve in section drawn to an enlarged scale showing one of the machine parts to which the improvements apply, and f Fig. 3 is a view in section of the air passage leading to the operating valve drawn to an enlarged scale as another part of the machine which may be embodied with the operating valve as a part of the machine.

ln the drawing l is a jarring cylinder having an exhaust valve seat 2. J is a jarring plunger having an air chamber C provided with an air inlet I and with an admission valve seat G1. B is a hollow valve body movable in the air chamber, C, having two internal diameters, 6 and 4, with choke holes, E, in the wall of 6, at its lower end. B1, at the lower end of the body, is an admission valve of diameter, 7, to seat upon C1. K is a spring arranged between the air chamber wall and the valve body tending to open the admission valve. B2 is a bushing of diameters 6 and 5 centered in, the valve body and firmly secured thereto. This forms a stop for the valve stem beneath and acts as a guide for the parts within. G is a cushion sleeve of diameters 3 and 5 in packed sliding relation to B2 and the upper end of the valve stem. It is limited in its movement by the top wall of the air chamber in one direction and by a shoulder, which engages the bushing B2 in the.. other direction, and it is provided with lugs on top to always permit the free passage of air from I to C. There is a hollow valve stem, V, having three eX- ternal cylindrical surfaces, V1 at the top,v

of diameter 3, in packed sliding relation with the cushion sleeve, Gr; V2, beneath, of diameter' 6, moving between stops in the valve body, and V3 at the lower end, of diameter 4l, both in packed sliding relation with B and V3 is carried down to exhaust. `Immediately below the piston V2 for a length about equal to the travel of the valve stem in the valve body, the diameter 4t is reduced to Q to provide clearance, Y, in which air can be stored when the piston, V2, is down against the shoulder on valve body at E, for a pur pose to be disclosed. Pressure is admitted to the interior of the valve stem thru ports, H, arranged below the admission valve and carried thru ports X, in the wall of V1, into theannular space above the piston V2. D is a double faced exhaust valve of which one face, D1, cooperates with the valve seat 2, and of which the other face, D2, cooperates with the seat 11 provided in the lower end, V2, of the steln V. .S is a by-pass choke sleeve, slidably mounted on the valve stem atVz, Tt is traversed on V by stops on the lower end of the chamber C, as indicated by an annular surface beneath the. pins 99 above the flange on S' thru which the choke holes pass, and it covers the ports, H, in its highest position. Fig. 3, in the air inlet I, there is a 'choke valve of whichrthe faces R and X, are re' versely tapered and one of the elements, 13, is of the form of a spring pressed plunger connected by a duct 14 with the space beneath the plunger, J. This plunger is attached, as usual, to a jarring table, T, which drops luptao. an' anvil, Z, while the plunger Mounted above the air chamber C,

chamber, C, surrounds it on all sides, and its weight only rests upon the spring K. ln this position, also, the valve D is held down upon the exhaust seat 2. lrVhen pressure enters the chamber, C, it passes thru the passage l5 in the choke sleeve Si under the plunger J and causes it to rise carrying with it the sleeve, S, and the valve body, B, on spring, K, until the valve body stops against the piston V 2, after which the continued upward movement of J compresses the spring l until C1 meets B1, and cuts off the air supply. At this point the additional lifting force oi the sprin e' l must be less than the load carried on valve seat 2 by a liberal margin, to insure atightly closed exhaust as the plunger continues to rise by momentum and liits the valve stem, V2, at its seat, ll, away from the valve face, D2. Art this time the ports H are closed by the sleeve S and the air within the valve stem immediately escapes reducing the pressure in the annular space above V2 to that oi' the exhaust, without atleet-ing the Apressure beneath the plunger J. rlhe way is thus prepared for quick and positive action in the opening or' the jarring cylinder to e2;- haust. rlhe air trapped in the clearance space, Y, due to the restricted area of ports E immediately expands lifting D away from its seat 2 while air entering thru the choke holes, E, carriesthe valve stem up at a predetermined rate faster than the table can fall by gravity, but under control, to mini mine the velocity ot impact between the valve stem V2 and the cushion sleeve Gr. Hitherto in air thrown valves for a like. purpose, the valve stem, V2, has struchr the cap on the valve body above it such high velocities as to be very destructive. The cap bolts have frequently been broken and the valve parts have been Aupset in a way to prevent their proper action. l-lere the reduced momentum is caught by the cushion sleeve, G, and B2 maynotmeet V2 until near the end of the falling movement, when the velocity of impact is slow in comparison with the velocities previously attained by air thrown valve stems.

lWhen impact occurs between V2 and G, the latter is naturally in its lowest position resting on its shoulder against B2, and the force of impact will naturally lift G away from E2 a shortdistance but G will immediately return to its shoulder and hold V in an advanced position as the table falls causing the exhaust to'close and trap air in the jarring cylinder before the jarring blow is struck, thus saving in air consumption while reducing the objectionable rebound, which tends to laminate the sand and prevent the uniform adhesion desired. litherto in air thrown jarring valves it has been diillcult to produce the desired effect to which the cushion, 9, also contributes.

Further than this, the double seated valve, D, acts in ell'ect lilre a pilot to prepare the way for a wide open exhaust with the least possible overrun in the rising table beyond its position when exhaust begins. This. is advantageous in plain machines because it makes substantial uniformity in length oi strolre possible, and it is especially desirable in slioclrless machines where an overrun of the table tends'to put the table and anvil out oi"l step with each other, causing the machine to run more or less wild, striking blows at irregular intervals which vary in intensity and sometimes miss altogether as the table rides on air. `When the valve stem stops ag uinst the exhaust seat 2, the plunger J continues to fall and with it the valve body, B, until B2 stops against V2, after which a short ii lther movement of J takes place which carries C away from B, admitting` pressure again to the jarring cylinder, for another stroke. This opening ol the admission valve again puts the valve body in immersed equilibrium and the spring K lifts it to th wide open position shown in TEig. 2.

lt has been observed that the valve stem in rising, under the pressure admitted thru the choke holes, E, will bevstopped and held from a further upward movement by the cushion sleeve G, and it should be pointed out that this follows from the relative areas nested and opposed to each other in packed sliding relation having concentric surfaces adapted to Contact together. Some latitude is permissible in these relative areas but not a great deal, and, to illustrate suitable proportions, care has been taken to malte the descriptive numbers applied to the several diameters, proportional to the actual diameters reqnired, beginning with 3 for the diameter of V1, and ending with 7, for the diameter oi' the valve B1.

ln the drawings the parts are shown in the positions which they occupy when the air is turned ori from the inlet I at some point outside of the machine.

Theoperation may be recapitulated as follows: f

Vihen air under pressure is turned on to lift the plunger J, it passes the choke holes l5 in the sleeve S entering the jarring cylinder l below the plunger J, lifting the 'plunger and table and the area of the holes l5 limits the speed el the plunger and table. The valve ll, when present, performs a similar function but with respect to the load on the table. lf the load on the table is comparatively light,

the valve at R may be assumed to remain in the position shown in Fig. 3, but if the load is comparatively heavy the pressure under the plunger required to lift it, also acting on the movable seat element 13, of the valve lifts it against its spring, thus increasing the area of the fluidway and adjusting the air supply to the load.

The rapid change of pressure under the jarring plunger would naturally cause the seat element 13 to dance and to avoid dancing the choke plug P is introduced in the air passage between the jarring cylinder and the cylinder enclosing element 13. In this way the average pressure beneath the jarring plunger will be communicated to the element 13, and l the objectionable dancing feature will be very much reduced. Under conditions of comparatively uniform loading it will not be necessary to introduce the choke plug P (Fig. 3) anda clear passage I, Fig. 2, may be substituted therefor, leaving the valve casing, C, without the passage lll, shown in Fig. 3.

Air under pressure enters not only the jarring cylinder 1 and lifts the plunger J, but also enters the chamber in the stem V by way of I-I, and passes thr'u the ports X into the annular space over V2. The admission valve B, is held open by the spring K. In rising the plunger lifts the sleeve S covering ports I-I, thus excluding the interior l of stem V from the ingress of air under pressure. The pressure in the stem V, acting through the holes X, upon the piston head of the valve stem, serves with the direct pressure on V1, to hold down the exhaust valve D. As the plunger rises the stem V remains stationary and the admission valve seat C1, contacts with the valve face Bl, closing air admission, thereupon through the lost motion connection 12 the ports 1l are uncovered and the interior of the stem V connected to exhaust as is also the space over V2. The result of this is that air trapped in Y due to the restricted area of ports E as well as air entering through holes E throws the stem upward with a quick motion at first and slower motion thereafter due to the restricted area 'of the holes E, and this upward motion of the stem V opens the exhaust wide and quickly.l The cushion G receives the impact of the stem and cushions it so that the valve body B is not subjected to jars 4or hammer blows. The plunger now falls and the lost motion connection l2 as well as the advanced position of G causes the valve I) to close the exhaust and to trap air under the plunger so that the fall of the plungeris checked, thus insuring that the mold or flask, which is falling with the table, is in good contact with it when the blow is struck. A short distance before impact occurs, the valve stem at V2 meets the bushing B2 and stops the valve face B1, while the valve seat C, continues to move thus opening the jarring cylinder to live air followed by a wider admission. The parts thus assume the position shown in Fig. l, the spring K having. lifted the body B and opened the admission valve for a repetition of the described jarring operation. 4

It will be obvious to those skilled in the art to which the invention relates that modifications may be made in details of construction and arrangement and in matters of mere form without departing from the spirit of the invention which is not limited to such matters or otherwise than the prior art and the appended claims may require.

I claim:

1. In a jar ramming molding machine an air chamber having main inlet and exhaust ports therein for admitting air to and exhausting air from said chamber and a spring pressed admission valve body and a hollow valve stem arranged in nested relationv and adapted to supply an exhaust air, piston and cylinder provisions between the stem and the body, a sleeve valve having sliding connection with the stem, and a double faced exhaust valve having lost motion connection with the stem and of which one face cooperates with the stem and of which the other i face controls the main exhaust port, there being inlet ports to the interior of the stem and inlet and outlet ports for the piston and cylinder provisions.

2. In a jar ramming molding machine an air chamber having main inlet and exhaust ports therein for admitting air to andQexhausting air from said chamber and a spring pressed admission valve body and a hollow valve stem arranged in nested relation and adapted to supply an exhaust air, a piston surface and an air space having restricted entrance and provided between the body and stem for shifting the latter, a by pass sleeve valve having sliding connection with the stem, and a double faced exhaust valve having lost motion connection with the stem, there being ports through the wall of the stem opening to said air space having restricted entrance and to said chamber below said main admission port. j

3. A jar ramming molding machine having a jarring plunger cylinderprovided with an exhaust and having a jarring plunger, an air chamber carried by the plunger and having an opening to exhaust and an air inlet, a tubular spring pressed admission valve body movably mounted in the chamber and providing cylinder air space in restricted communication with the interior of the chamber, an endwise movable hollow valve stem closed at its upper end and having an external piston surface arranged in said cylinder air space and 1 said stem being ported above the piston surface to said piston space and below said admission valve to said chamber, a double faced exhaust valve cooperating with the plunger cylinder exhaust and with'the interior of the stem and having 10st moti-on Connection With the open end of the stem, and a by-pass sleeve shdably mounted on the stem and havlng restrlcted air passages and havlng Hang@ con necton with the air chamber and adapted to control zur admlsslon to the lnterlor of the stem.

v WILFRED LEWIS. 

